Script is by Carney and his brother Kieran. Ed Guiney is producing for Element, which is also taking Irish rights for its newly formed distribution arm headed by former Momentum exec Audrey Shiels.

In fact, Carney has shot “Zonad” once before — his IMDb entry lists it as a 2003 production, starring Cillian Murphy. This was actually a homemade pilot — Guiney calls it “a glorified read-through on video” — which has never seen the light of day. Indeed, Guiney claims that neither he nor Carney are quite sure where the master tape actually is, although a clip of Murphy in “Zonad” has inexplicably found its way onto YouTube.

Carney filmed the pilot as part of his characteristic development process, which often involves a lot of shooting just to see what emerges. He and Guiney toyed with trying to set “Zonad” up as a TV series before returning to the idea of a feature.

The success of “Once,” which won the audience prize at Sundance and has gone on to gross $7 million Stateside via Fox Searchlight, gave them the impetus to take the plunge into production with the much-revised “Zonad” script.

The decision to make “Zonad” emphasizes Carney’s determination to stick close to his Irish roots and the low-budget aesthetic that served him so well with “Once.” Although “Town House” comes next, he won’t be quitting Ireland permanently for the U.S.

Nonetheless, his stock continues to rise in Hollywood. After 13 weeks in release, “Once” is still going strong in niche locations, and its momentum could carry it all the way into awards season. Steven Spielberg recently told USA Today, “A little movie called ‘Once’ gave me enough inspiration to last the rest of the year.”

The irony is that the movie, which had its world premiere as a rough cut at the Galway Film Fleadh in summer 2006, was subsequently rejected by several larger European fests, including Edinburgh, Locarno, London and Rotterdam. Selection for Sundance was the big break, although producer Martina Niland recalls that many people warned her that such a small film would sink without a trace there.

Actually, the pic screened six times to packed houses in Park City, was picked up by Summit for worldwide sales, won the audience vote and was bought by Fox Searchlight in the U.S. for a reported $1 million — seven times its production budget.

“It’s one of those strange stories where the Americans pick up on something that the Europeans don’t get,” comments Irish Film Board topper Simon Perry. “All those European festivals just didn’t see enough in it.”

This year’s Edinburgh fest has tried to make up for lost ground by selecting “Once” in its “Directors’ Showcase” section, where it screens Aug. 24. Many other foreign fests are queuing up to book the movie as it embarks on its foreign rollout this fall.

Perhaps it’s a commentary on the blinkered mindset of Euro fest directors that “Once” fell beneath their notice first time around. But Summit’s David Garrett points out that the movie was also shunned by most U.S. buyers at Sundance until it won the audience award. “There wasn’t a bidding frenzy until Sundance had concluded,” he recalls.

Now, “Once” has become a fascinating test of the power of the U.S. market to create a worldwide hit out of a tiny foreign movie that otherwise would have slipped between the cracks. “Once” performed poorly on its release in Ireland, where auds normally embrace any halfway decent local effort. But that was back in March, before the U.S. release had cast its golden glow.